Reduced parasympathetic activity may be found in individuals under mental or emotional stress, suffering from panic, anxiety or worry, depression, high blood pressure, heart disease and many other disorders.
Some devices, such as those developed by the Institute of Heart Math in Boulder Creek, Calif., have been developed to aid users in identifying and/or improving parasympathetic activity. Such devices may produce simple metrics associated with a meditation state, or entrainment, in which the heart rate varies with the breath as measured by heart rate alone. These and similar devices typically provide metrics based on measurements from a single sensor, such as a heart rate monitor. Additionally, these and similar devices may be limited to use in controlled environments and/or may not tolerate noise arising from a subject undertaking everyday activities while using such devices.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one example technology area where some embodiments described herein may be practiced.